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The Effects Of Emergency Contraceptive Pill On Periods

An emergency contraceptive pill (ECP), often referred to as the morning-after pill or plan B, is a vital tool for preventing an unintended pregnancy after unprotected sex (when no contraception is used) or contraceptive failure (for example, when the condom breaks, slips, or leaks during sex). However, some users report changes in their periods following ECP use. This blog explores how an ECP may affect your periods.

How Does An Emergency Contraceptive Pill Work?

An emergency contraceptive pill (ECP) works primarily by preventing or delaying ovulation, that is, the release of an egg from the ovary. If ovulation is delayed, fertilization and pregnancy can be prevented, in case unprotected sex or contraceptive failure has occurred.

An ECP can help prevent an unintended pregnancy if taken as soon as possible within 72 hours (3 days) after the first episode of unprotected sex has occurred. It doesn't work if a pregnancy has already begun.

how does a emergency contraceptive pill or ecp or morning after pill or plan b or ipill or unwanted 72 pill works

Effects Of An Emergency Contraceptive Pill On Periods

Timing & Duration

The most common effect of an ECP is the timing of the next period. It can arrive earlier or later than expected, usually by a week, and may be slightly longer than usual.


Additionally, some individuals may notice a change in the flow of their next period, experiencing either lighter or heavier bleeding than usual.


Some spotting between ECP use and the next period is another possible effect of an ECP. This light bleeding can be confusing and worrisome for some, but it is generally not indicative of a serious issue.

Menstrual Cramps

An increase or decrease in menstrual cramps has been reported by some ECP users. However, these are typically temporary and should normalize in the subsequent menstrual cycles.

possible effect of emergency contraceptive pill or ecp or morning after pill or plan b or ipill or unwanted 72 pill on periods

When To Consult A Doctor

Experiencing some changes in your next period after taking an ECP is generally not a cause for alarm. However, if your period is delayed by more than a week, or if it is significantly heavier or lighter than usual, or if you have any other concerns, it is advisable to consult a doctor.


An emergency contraceptive pill (ECP) is a critical component of reproductive health, offering a second chance at preventing an unintended pregnancy. While changes in the next period after ECP use are common, they are generally not harmful. Understanding these effects can help users manage their expectations and reduce anxiety surrounding its use. Remember, always consult a doctor for personalized advice.


This blog, including its text, images, and infographics, are for educational purposes only and not a substitute for professional medical advice. For personalized advice, always consult a doctor.

Further Reading

For more details on this or related topics, refer to the papers listed in References below, the FAQs on the ECP page, or other blogs on the Learn page of our website


  • Contraception. Menstrual bleeding patterns following levonorgestrel emergency contraception. 2006.

  • World Health Organization. Emergency contraception. 2021.


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